Fully usable. But... this lens was originally designed for 35mm film use (same size frame as a FF DSLR like the Pentax K-1 or K-1 II). Accordingly, it was meant to give the user moderate wide angle to short telephoto general-purpose usage. On a DSLR camera of APS-C frame size, which are most, this sensor will produce a narrower FOV (Field Of View) so the 35mm end of this zoom will not avail the user of any wide angle at all. You would need a zoom lens starting with at least down to 24mm for general purpose usage on an APS-C camera.
Last edited by mikesbike; 03-02-2023 at 01:03 PM.